The miR-6779/XIAP axis alleviates IL-1β-induced chondrocyte senescence and extracellular matrix loss in osteoarthritis.

Background: Osteoarthritis (OA) is a long-term degenerative joint disease worsening over time. Aging and chondrocyte senescence contribute to OA progression. MicroRNAs have been confirmed to regulate different cellular processes. They contribute to OA pathology and may help to identify novel biomarkers and therapies for OA.

Methods: This study used bioinformatics and experimental investigations to analyze and validate differentially expressed miRNAs in OA that might affect chondrocyte apoptosis and senescence.

Results: miR-6779 was found to be significantly down-regulated in OA. Seventy-six of the predicted and miR-6779 targeted genes and the OA-associated disease genes overlapped, and these were enriched in cell proliferation, cell apoptosis, and cell cycle. miR-6779 overexpression remarkably attenuated IL-1β effects on chondrocytes by reducing MMP3 and MMP13 levels, promoting cell apoptosis, suppressing cell senescence, and increasing caspase-3, caspase-9 and reducing P16 and P21 levels. miR-6779 targeted inhibition of X-linked inhibitor of apoptosis protein (XIAP) expression. XIAP knockdown partially improved IL-1β-induced chondrocyte senescence and dysfunction. Lastly, when co-transfected with a miR-6779 agomir, the XIAP overexpression vector partially attenuated the effects of miR-6779 overexpression on chondrocytes; miR-6779 improved IL-1β-induced senescence and dysfunction in chondrocytes through targeting XIAP.

Conclusion: miR-6779 is down-regulated, and XIAP is up-regulated in OA cartilage and IL-1β-treated chondrocytes. miR-6779 inhibits XIAP expression, thereby promoting senescent chondrocyte cell apoptosis and reducing chondrocyte senescence and ECM loss through XIAP.